Hopes for survivors in a sunken ferry in the Philippines faded yesterday as rescuers suspended attempts to find some 171 passengers still missing from a collision in which at least 31 are known to have died.

The sinking of the MV St Thomas Aquinas, operated by the Manila-based 2GO Group – the Philippines' largest shipping operators – raised further questions about maritime safety in the archipelago where frequent storms, poorly maintained ships and weak enforcement of safety regulations have led to a slew of accidents.

Yesterday, further details emerged of the circumstances that led up to the sinking on Friday, while authorities warned the death toll could rise further today as stormy conditions forced rescuers to suspend their search.

The captain of the 11,000-tonne Thomas Aquinas was approaching the port of Cebu for an overnight stop on the way to Manila when he gave the order to abandon ship after the vessel – with 723 passengers and 118 crew – was hit by the cargo boat Sulcon Express 7, operated by Philippine Span Asia Carrier Corporation (PSACC) near Lawis Ledge, about 350 miles south of Manila.

The roll-on/roll-off Thomas Aquinas began "listing heavily" and sank within half an hour, said coast guard deputy chief, Rear Admiral Luis Tuason. He added that 171 passengers were still missing, with many feared to be stuck inside the vessel, now 100ft under water.

"There could be more bodies there but there were lines inside that our divers could get entangled in," said Rear Admiral Tuason yesterday, as he confirmed that four bodies had been recovered in the early hours.

The 2GO Group said that their vessel had been "reportedly hit" by the cargo ship.

Joseph Abaya, the Philippines' Transport and Communications Secretary, said the cargo ship had smashed into the right side of the ferry which had been travelling from Nasipit in Agusan del Sur province. "I guess it hit the ferry at a very vulnerable point, probably at its waterline or below the waterline so that it did not take long for it to sink," he said.

Danny Palmero, a former fisherman, responded to the ferry's distress call. He said: "We just picked up the survivors and left the dead in the water. I heard screams and crying."

One of the survivors, Jenalyn Labanos, 31, said the ferry quickly tilted to its side after the impact. She said the crash threw her and two companions to the floor of the restaurant before the lights went out. "I just thought to myself that I have to survive this. I left everything, my bag, my money and my passport," she said.

An official at the coastguard said it was "too early" to determine the cause of the collision. He said there had been foreign nationals on board, but added they were "all OK" except for a New Zealander who remained in hospital.

"We are aware of this shipping accident in the Philippines and are in touch with the local authorities," a Foreign and Commonwealth Office spokeswoman said in London. "We stand ready to offer consular assistance."

The company PSACC, previously known as Sulpicio Lines, operated the Dona Paz, which was at the centre of the world's worst peacetime maritime disaster in 1987 when 4,375 people died as the ship struck an oil tanker in the Philippines. PSACC vessels have reportedly figured in four maritime disasters with more than 5,300 fatalities.

Yesterday, no one from PSACC was available for comment.

"The crew distributed life jackets to the passengers and carried out emergency abandon-ship procedures," said a 2G0 Group statement. The Philippine Maritime Industry Authority (Marina) last year announced a crackdown on safety standards in ships with inspections of carriers across its critical ports – including Cebu. "People's lives are at stake," warned the Marina administrator Emerson Lorenzo.

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